Introduction
Sensitization to pollen plays a crucial role in the development of allergic disorder,1 which has been reported to lead to more serious allergic symptoms and to increase the risk of asthma.2-3. An interaction between the exposure to pollen and being sensitized to pollen allergens was detected that the effect was less pronounced in individuals who were sensitized to only one type of pollen, compared with who are sensitized to all types of pollen. Furthermore, as different pollen types are released at different periods of the pollen season, atopic individual sensitized to more than one type of pollen are experiencing a longer period of exposure, which may lead to a stronger effect on airway hyperreactivity and reduced lung function.4
Pollen season is related to the flowering season, for pollen has to be previously produced and emitted by mature flowers. Weather variables, mainly air temperature, sunshine and rainfall, together with CO2 are among the main factors affecting phenology and pollen production by plant.
The weather may be the most crucial factor because it can alter the starting and ending of pollination and affect the change of pollen season directly although there are several environmental factors such as greenhouse gases, the other air pollutants. Weather conditions may subsequently influence the occurrence of allergic diseases such as asthma, allergic rhinitis. A growing number of people are contracting allergic diseases caused by pollen because of weather change in the world.5
The start and end of the pollen season itself, as defined by airborne pollen, may be influenced by factors affecting pollen dispersal, and may not coincide exactly with the maturation of the flowers. Longer pollen season and larger the amount of atmospheric pollen could enhance the human exposure to allergic pollens. These might relate with an increase in allergic sensitization. As the sensitization rate to pollen has increased in children recently, allergic plants which is rapidly proliferating, has emerged as a dangerous element to allergic children. It is now essential to survey pollens around the patient for the management of pollen allergy.6-8
A number of studies on the climate change effects on allergenic pollen distribution have focused on analyses of observed pollen counts and their regression relationships with local meteorological factors. Ongoing climate change, through rising the concentration of atmospheric CO2 and temperatures, contribute to extension of seasonal duration and increase in multiple pollen load.8 In an experimental study, warming and changes in CO2 were demonstrated an increase in pollen production.9,10 Elevated CO2concentrations resulted in early pollen production from trees and greater seasonal pollen production.11,12 In addition, weather patterns influence the movement and dispersion of all aeroallergens in the atmosphere through the action of winds, rainfall and depending on the atmospheric stability.
This study investigated the reasons for recent rising pollen allergy and the sensitization rate to pollen has increased in children recently, and the relationships between the changes in start and end dates of pollination and weather changes for the past 22 years in Seoul metropolitan area. The results of the analysis are used in an attempt to predict trends in start dates in future. This study has important implications for the use of phenology as an indicator of weather changes and also for recent rising pollen allergy in children in Korea.